This application will interdigitate with an ongoing longitudinal case-control study, HL-35333, "Carotid Atherosclerosis Follow-Up Study." HL-35333 comprises 280 individuals older than 45 equally divided between males and females, half with and half without CAD evaluated for risk factors at baseline and with completed follow-up with yearly B-mode for 3 years. It has quantified the interassociations of angiographically defined coronary artery disease (CAD) and CAD risk factors with progression. Recently the NIH funded a continuation of this effort to review existing ultrasound tapes from this study in order to additionally evaluate the associations of all these factors with extracranial carotid arterial dimensions (ECAD: interadventitial and lumen diameters) and change in ECAD over time. More recently the investigators have received NIH funding to explore, in an ancillary study in another cohort (Cardiovascular Health Study, CHS), another aspect of vascular disease that is dependent on arterial dimension measurement and that can be measured non-invasively: flow-mediated (endothelium-dependent) brachial artery vasodilation. The multicenter CHS ancillary proposal aims to quantify this in CHS participants and relate it to incident CHD. Precise quantification of coronary status is not available in CHS. Furthermore, although non-invasive measurement of brachial artery reactivity provides considerable potential strengths for use in epidemiologic studies (compared to studies of coronary artery reactivity), it is only inconsistently associated with CAD in the literature. The investigators state that the proposed new study (building on availability of a well characterized group of individuals already identified as with and without CAD in the HL-35333 population and strengths in imaging and image analysis of arterial dimensions) will directly address the question of the relation of non-invasively measured flow-mediated brachial artery dilation with CAD by quantifying this in the HL-35333 cohort and relating it to CAD status, risk factors, ECIMT, and ECAD. They add that this study will thus also complement the CHS ancillary study. Finally, they state that pilot data in a small subset of the HL-35333 population support the feasibility and likely informativeness of this study.